18 Answers

I think astronomers probably are being presumptuous about their understanding of the universe and their interpretation of its history and future from lights from such extreme time/distances and neither big crunch nor endless expansion is accurate or complete.

The universe grows into its basic teenage form and gets all awkward. It gets into a few really messy relationships and its growth is stunted. It gets a dead end management job related to physics and goes home every night to watch re-runs of Degrassi Junior High. The good news for us is that this all takes a very long time and the universe comes from a family with longevity (on her mother’s side).

I believe that the “big crunch” theory is gradually loosing adherents.

The most supported theory is that there will be an endless expansion – forcing galaxies to become more distant from each other.

I don’t remember where I read this – but another factor of the “endless expansion” theory is that matter will eventually loose it’s cohesiveness (the “strong” force in quarks, I believe). As the universe expands the ability of all matter to “stick” together will fail. This means that atoms will begin drifting apart as the galaxies are now – eventually leading to the slow “disintegration” of all things that have mass.

Doesn’t gravity get weaker by the square of the distance? That would imply less and less force to hold things together as the universe expands, hence, ever expanding universe! (Can you tell I’m no astrophysicist?)

Recent observations suggest that the expansion of the universe will continue forever. If so, the universe will cool as it expands, eventually becoming too cold to sustain life. For this reason, this future scenario is popularly called the Big Freeze.

The future of an expanding universe is bleak. If a cosmological constant accelerates the expansion of the universe, clusters of galaxies will rapidly be driven away from each other, leaving observers in different clusters unable to either reach each other or sense each other’s presence in any way.

Eventually the supply of gas needed for star formation will be exhausted. Once the last star has exhausted its fuel, stars will then cease to shine.The stellar remnants left behind are expected to disappear as their protons decay, leaving behind only black holes which themselves eventually disappear as they emit Hawking radiation. Ultimately, if the universe reaches a state in which the temperature approaches a uniform value, no further work will be possible, resulting in a final heat death of the universe.

Big Rip is where the acceleration caused by dark energy eventually becomes so strong that it completely overwhelms the effects of the gravitational, electromagnetic and weak binding forces. As a result, all material objects in the universe, starting with galaxies and eventually (in a finite time) all life forms, no matter how small, will disintegrate into unbound elementary particles and radiation, ripped apart by the phantom energy force and shooting apart from each other.

I’m one of those people that, with their limited understanding of physics, is willing to bet there was never a beginning and there won’t be an end. I’m willing to bet it’s more complicated than that :D